Here is the full list of all 24 Mini Ghost achievements.
Beat the game in less than 45 minutes
Beat the game without dying.
Beat the game without using secondary weapons
Beat the game without dying or being assisted by doctors
Change a friend's character while he/she is playing
Reach boss zone 1 without killing any monster or being damaged by them
Pick up any item in less than 16 seconds
Find all Twitch Friends
Destroy boss zone 2 with a laser
Destroy boss zone 1 with a rocket
Kill boss zone 1 receiving no damage from it
Beat the game
All items in inventory
Buy everything available
Obtain card 4
Kill boss zone 3 receiving no damage from it
Destroy boss zone 3 with a mine
All hp bar unlocked
Find secret room
Find night vision goggles
Obtain card 3
Kill boss zone 2 receiving no damage from it
Destroy a boss in less than 40 seconds
Obtain card 2